This invention is generally directed to polymers and processes for the preparation thereof. The process of the present invention in embodiments relates to the preparation of a polymer, which polymer can be selected as a carrier powder coating, and more specifically a process for the preparation of polymeric particles with for example, a volume average particle size diameter of from about 0.05 micron to about 5 microns, and preferably from about 1 to about 5 microns in volume average diameter, as determined for example by known methods, such as a Coulter Counter. In embodiments the present invention also relates to developer compositions comprised of carrier particles coated with a continuous, or semicontinuous layer of a polymer prepared by the processes illustrated herein.
More specifically the present invention is directed to processes for the preparation of polymers wherein there is formed a complex between for example, polyvinyl acetate, iodine, and iodide, and there is eliminated, or minimized, undesirable foaming and fouling of the reactors selected, thereby enabling the process to be very useful on a large manufacturing scale. The carrier particles containing the polymer generated as illustrated herein, and a second polymer, such as polyvinylidene fluoride, or enable a wide carrier triboelectric range. Developer compositions comprised of the carrier particles illustrated herein and prepared, for example, by a dry coating process are useful in electrostatographic or electrophotographic imaging systems, especially xerographic imaging, digital imaging, and printing, inclusive of color printing processes. Furthermore, in the aforementioned imaging systems the triboelectric charge on the carrier particles can be preselected depending on for example, the polymer composition and dispersant component applied to the carrier core.
With the carrier compositions and process of the present invention there can be formulated developers with selected triboelectric charging characteristics and/or conductivity values in a number of different combinations. Thus, for example, there can be formulated in accordance with the invention of the present application developers with conductivities of from about 10.sup.-6 ohm-cm to about 10.sup.-17 ohm-cm, and preferably from about 10.sup.-8 ohm-cm to about 10.sup.-6 ohm-cm, which conductivities are determined in a magnetic brush conducting cell, and a wide carrier triboelectric charging value of from about -30 to about +70, and in embodiments of from about -15 to about +20 microcoulombs per gram on the carrier particles as determined by the known Faraday Cage method. Thus, developers can be formulated with constant conductivity values with different triboelectric charging characteristics, or with constant triboelectric charging values and different conductivities.